non/spire — pull request #14 by tixxit (2012-04-10 16:17:04+00:00)
Title: Add Signed type class, remove sign(um) and abs from Ring.

Adds a new Signed[A] type class for working with signs. Numeric,
Fractional, Integral all extend it, but Ring, EuclideanRing, and Field
do not. Also adds tests, which found a bug in Real (commit fixes this
bug).